Arc welding is the most widely used means of joining metals and alloys by fusion techniques in industry today and is of profound importance to industrialised and manufacturing countries. An arc welding process uses the heat generated by an arc struck between an electrode and the workpiece to melt and fuse metal in the joint area. The main arc welding processes in use today include MMA, MIG, TIG, FCAW, MCAW and submerged arc. In most arc welding processes the electrode is consumed to form weld metal, but it may also be a non-consumable electrode, as in TIG and plasma welding. Each process provides a protective gas cover for both the consumable and the molten weld pool to prevent oxidation or contamination. This may be in the form of an external shielding gas.
When using arc welding it is important that welders use the correct shielding gas flow rate. Using a flow rate that it either too high or too low can result in welding defects being introduced into the weld area. Using too much gas can result in turbulence which reduces the mechanical strength of the weld. Using too little gas can result in porosity in the weld area which also reduces the strength of the weld. Oxidation of the weld surface can also result from an incorrect gas flow. Using too much gas also effectively wastes money. Therefore users should be checking their flow rates each day or after breaks. Usually most welders only check the flow rate once.
The most common way of checking flow rate is with a flow meter either attached to the regulator of the gas supply cylinder or integral with the regulator. However this method can create problems because it doesn't take into account any leakage or pressure losses within the hose connecting the cylinder to the welding power source or the welding torch itself. A more accurate technique is to provide the welder with his own personal flow meter, such as a simple bobbin or turbine flow meter, so that he can measure the gas flow rate at the torch. However, very few welders use such a device, often quoting that such units are either easy to break, lose or too expensive to purchase.
There is therefore a need to provide a device which is convenient to use and difficult to lose or break.
The invention aims to provide a small but accurate flow meter built into the cylinder guard that the welder can use whenever he wishes. As the flow meter is close to the cylinder valve and regulator it is convenient to use as he starts work.